 
 (def initial-rendering-data
   {:scale          350 ; How many pixels a distance of 1 in the complex plane takes up
-   :x0             -3
-   :y0             1.2})
+   :x0             -3 ; the x co-ordinate of the top-left pixel in the canvase
+   :y0             1.2 ; the y co-ordinate of the top-left pixel in the canvase
+   })
 
 (defonce app-state (atom {:escape-radius 10000
                           :rendering-data initial-rendering-data}))

  (aset overlay-canvas "height"(.-innerHeight js/window)))

(defn render-mandelbrot!
  [{escape-radius                          :escape-radius
    {:keys [scale x0 y0] :as render-state} :rendering-data}]


    (.putImageData context idata 0 0)

    (.log js/console "Done in: " (int (* 1000 (/ (* height width)  (- (.getTime (js/Date.)) start)))) "px/s")))

(defn add-overlay-rectangle!
  "Adds a rectangle to the overlay canvas (and optionally clears all other rectangles)"
